Pyrolysis of cotton stalks and utilization of pyrolysis char for sustainable soil enhancement and carbon storage

Transcription

1 Engineering Conferences International ECI Digital Archives Biochar: Production, Characterization and Applications Proceedings Pyrolysis of cotton stalks and utilization of pyrolysis char for sustainable soil enhancement and carbon storage Sebastian Schaffer University of Natural Resources and Life Sciences, Austria Tobias Pröll University of Natural Resources and Life Sciences, Austria Rafat Al Afif University of Natural Resources and Life Sciences, Austria Christoph Pfeifer University of Natural Resources and Life Sciences, Austria Follow this and additional works at: Part of the Engineering Commons Recommended Citation Sebastian Schaffer, Tobias Pröll, Rafat Al Afif, and Christoph Pfeifer, "Pyrolysis of cotton stalks and utilization of pyrolysis char for sustainable soil enhancement and carbon storage" in "Biochar: Production, Characterization and Applications", Franco Berruti, Western University, London, Ontario, Canada Raffaella Ocone, Heriot-Watt University, Edinburgh, UK Ondrej Masek, University of Edinburgh, Edinburgh, UK Eds, ECI Symposium Series, (2017). This Abstract and Presentation is brought to you for free and open access by the Proceedings at ECI Digital Archives. It has been accepted for inclusion in Biochar: Production, Characterization and Applications by an authorized administrator of ECI Digital Archives. For more information, please contact

2 Biochar: Production, Characterization and Applications August 20 25, 2017 Hotel Calissano, Alba, Italy Pyrolysis of cotton stalks and utilization of pyrolysis char for sustainable soil enhancement and carbon storage Sebastian Schaffer, Tobias Pröll, Rafat Al Afif, Christoph Pfeifer Department of Material Sciences and Process Engineering University of Natural Resources and Life Sciences, Vienna, Austria

3 Outline Why cotton stalks? Rotary kiln pyrolysis technology Considered process configuration and performance Pyrolysis char for soil carbon storage Conclusion and outlook Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 1

4 Current Situation Source : Major amount of cotton produced with low environmental standards Thermal treatment necessary to avoid survival of pests Leads to high local emission and pollution Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 2

5 Cotton stalks Ligno cellulosic residue. Major part of biomass in cotton crops. Approximately 75 million tons of cotton waste per year High potassium and chlorine content causes ash melting and corrosion issues upon combustion or gasification systems Pyrolysis treatment at C avoids ash melting. Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 3

6 Sustainable biomass life cycle Re use or re cycling Cultivation, harvesting and processing Industrial utilization Energetic utilization By products By products Soil improvement Priority is given to industrial utilization (food, feed, raw material) By products for energetic use appear in all process steps Closed life cycle includes sustainable soil management Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 4

7 Considered process: Rotary kiln pyrolysis Source: Heated horizontal drum, atmospheric pressure, C Product distribution depends on temperature and throughput Robust and industrially proven technology Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 5

8 70 t/d industrial waste pyrolysis plant Burgau/Günzburg (operated ) Source: Kreisabfallverband Günzburg, online Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 6

9 Previous work: 3 MW th pilot plant Dürnrohr Operated , feed: wheat straw, others Reference: Kern et al. Journal of Analytical and Applied Pyrolysis 2012;97:1 10. Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 7 Photograph: S. Kern, TU Wien

10 Path of elements (wheat straw, 0.5 t/h, 550 C) Share in char, gas and oil Source: Stefan Kern, Master Thesis, TU Wien, Chlorine and potassium stay in the char fraction. Char not suitable as fuel for boilers soil application. Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 8

11 Methodology and assumptions Simple process configuration, char as a product Direct gas combustion without cooling Mass and energy balance model based on pilot plant data Similar splitting ratios for wheat straw and cotton stalks Unit Cotton stalks Wheat straw Ash wt% Volatile matter wt% Fixed carbon wt% Carbon wt% Hydrogen wt% Nitrogen wt% Sulfur wt% Oxygen wt% Net calorific value (LHV) MJ/kg Sources: ECN/Phyllis2 and Ahmed et al. Journal of American Science 2010;6: Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 9

12 Considered process configuration Furnace comb. air AMB Pyrolysis comb. air AMB. Furnace Biomass ORG Cyclone Process heat Pyrolysis reactor Pyr. gas Chimney ORG Char Simulation tool: IPSEpro / PGP Lib model library + own unit models Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 10

13 Energy flow diagram Furnace comb. air Pyrolysis comb. air Biomass El. power 0.4 El. power Comb. air fan 2 Comb. air fan El. power El. power Exhaust Exhaust fan Air preheater 2 fan 1 Air preheater 1 Cyclone Pyr. gas Furnace F Boiler Heat loss Heat loss Heat loss Chimney Process heat All values in kw Pyrolysis reactor Heat loss Char Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 11

14 Carbon flow diagram Furnace comb. air 0.3 Air preheater Air pre- Exhaust 1 heater 2 fan Pyrolysis comb. air Biomass Pyr. gas Cyclone Furnace All values in kg/h Exhaust fan 2 C 92.6 Chimney Pyrolysis reactor Char Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 12

15 Ash flow diagram Furnace comb. air 0,0000 0,0000 Pyrolysis comb. air Biomass. Pyr. gas Eco. 1 Eco. 2 0,0008 0,0008 0,0008 Cyclone 3,8867 0,0031 Compressor 0,0008 Eco. 3 Furnace 0,0031 All values in kg/h Compressor 0,0039 0,0039 0,0039 Chimney 21,5925 Pyrolysis reactor 17, , ,5886 Char Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 13

16 Pyrolysis char for soil carbon storage How long will the carbon stay in the soil? Several studies available in the literature K.A. Spokas (2010): half life > 1000 years for O:C molar ratio < 0.2 (Carbon Management 1(2), ) O:C < 0.2 easily reached in rotary kiln pyrolysis Soils as safe and sustainable carbon sink Positive side effects from storage (soil quality increase) Equal or better climate change mitigation effect compared to electricity generation from biomass* *Pröll et al. (2017). Energy Procedia 114: Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 14

17 Conclusion / Outlook Sustainable biomass utilization involves nutrient cycles and soil management. 40% of the carbon captured by cotton crops is stored in the char Biomass derived charcoal can serve as long term carbon storage Cotton good test case for biochar application as it is in the nonfood domain Further work required on Conversion process and char properties/composition Char application effects on soil quality and environment Schaffer et al., Biochar Conference, August 20 25, 2017, Hotel Calissano, Alba, Italy 15

18 Biochar: Production, Characterization and Applications August 20 25, 2017 Hotel Calissano, Alba, Italy Questions?? / Discussion Contact: Sebastian Schaffer or Tobias Pröll sebastian.schaffer@gmx.at; tobias.proell@boku.ac.at